Read voltage in IO-ATC8/AI8 module issue

[navigatoru]

Hi guys, 

 

I have an IO-ATC8/AI8IO module, connected to a V1210 PLC. I am trying to read the values from a humidity sensor which has the output 0-3V in an AI0 of the above module. The AI0 is configured as 0-10V Type, No Filter, Normal Mode. 

I am reading this value in a MI10 operand. 

The issue is that I am reading in PLC the following values: 5 or 6. 

Reading with a voltmeter directly from the sensor's output, I am able to read the output voltage values properly (0-3V, and changing the humidity around the sensor, the voltage read with the voltmeter is changing accordingly). 

 

Do you have any idea why I am not able to read the proper voltage value in my PLC? 

 

Cheers, 

Marius

 

[cantcliff]

Do you have a linearize function for the operand?

 

Does the input value change as well or does it always read 5 or 6?

 

Is it possible that the wiring is incorrect?

[Damian]

Jumper settings?  Wiring and common connection?  MI10 overwritten somewhere else in program?

[navigatoru]

Hi Cantcliff / Damian, 

 

Thank you for your input. It helped me to find the issue. First one it was the jumper settings in the AIO module. Second one it was a loose connection between sensor and AIO module. 

Now, I am able to read values in the PLC. 

 

Unfortunately, the PLC is reading a value of 1234 when I am reading with a voltmeter from the sensor a value of 2.999V and a value of 648 when I am reading with voltmeter from the sensor a value of 1.566V. The output range of the sensor is between 0-3V. The AI Mode is configured on Fast.

Not sure if in the PLC I have to read exactly the values that I am reading with the voltmeter, or the PLC is doing some sort of scaling for the analogue inputs?

 

Appreciate your input. 

 

Cheers,

Marius 

 

Later edit: I watched the webinars regarding the linearization and I found what happened. The PLC is doing the linearization (scaling) between what is reading from sensor and internal bits of the PLC. I am doing a new linearization and I got my values - the real humidity

 

Cheers, 

Marius